Detect Comeau compiler version with its id

Decode decimal digits from __COMO_VERSION__ to compute the version
number components.  See documentation at:

  http://www.comeaucomputing.com/4.0/docs/userman/predefs.html
  http://sourceforge.net/p/predef/wiki/Compilers/#comeau-chttpenwikipediaorgwikicomeau_cc2b2b

Modules/CMakeCXXCompilerId.cpp.in

@@ -10,6 +10,9 @@
 
 #if defined(__COMO__)
 # define COMPILER_ID "Comeau"
+  /* __COMO_VERSION__ = VRR */
+# define COMPILER_VERSION_MAJOR DEC(__COMO_VERSION__ / 100)
+# define COMPILER_VERSION_MINOR DEC(__COMO_VERSION__ % 100)
 
 #elif defined(__INTEL_COMPILER) || defined(__ICC)
 # define COMPILER_ID "Intel"